International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064
Index Copernicus Value (2013): 6.14 | Impact Factor (2013): 4.438
Volume 4 Issue 2, February 2015
www.ijsr.net Licensed Under Creative Commons Attribution CC BY
Design and Photo-Lithographic Fabrication of
Microstrip Patch Antenna
Sanjay M. Palhade1, S. P. Yawale
2
1Department of Physics, Shri Shivaji College, Akola, India
2Department of Physics & Electronics, Government Vidharbha Institute of Science & Humanities, Amravati, India
Abstract: Microstrip patch antennas are generally fabricated by photo-lithographic method. Photo-lithographic method produces
highly accurate etched pattern for the microstrip patch. Fabrication accuracy is very critical as the microstrip patch antennas are
narrow band resonant structures that usually operate in the microwave bands. Fabrication errors in the patch dimensions will shift its
resonant frequency. Photo-lithographic method is a chemical etching process which removes the unwanted metal regions of the metallic
layer. This paper describes the design, simulation and the step by step fabrication process for a rectangular microstrip patch antenna .
Keywords: Microstrip Patch Antenna, EMCoS Simulation, Photo-lithography, Fabrication, UV light
1. Introduction
Microstrip patch antennas (MSPAs) consist of a metallic
patch printed on a grounded and electrically thin dielectric
substrate. The radiating metallic patch can assume any shape
but regular geometrical shapes are generally employed.
Regular geometrical shapes simplify analysis and provide
performance prediction. Rectangular and circular geometries
are common. The rectangular patch has to be half wave
length long at the resonant frequency [1]. Thick substrates
with a low value of dielectric constant εr are generally used
to enhance the fringing fields, which account for the
radiation from microstrip patch antenna [2 ], [ 3].
This paper describes the designing and fabrication of a
rectangular microstrip patch antenna. The microstrip patch
antenna is designed and simulated using EMCoS Antenna
VirtualLabTM
[4] electromagnetic simulation software, which
is based on the Method of Moment (MOM) technique of
solving electromagnetic problems [5]. The designed
microstrip patch antenna is fabricated by photo-lithographic
method. Photo-lithographic method is a chemical etching
process which removes the unwanted metal regions of the
metallic layer. Photo-lithographic method produces highly
accurate etched pattern for the microstrip patch. Fabrication
accuracy is very critical as the microstrip patch antennas are
narrow band resonant structures that usually operate in the
microwave bands. Fabrication errors in the patch dimensions
will shift its resonant frequency [6].
This paper is divided into two parts. The first part deals with
design and simulation of conventional half wavelength long
rectangular microstrip patch antenna, resonant at TM10 mode
frequency 1950 MHz. The second part describes the photo-
lithographic fabrication of the microstrip patch antenna
designed in the first part.
2. Rectangular Microstrip Patch Antenna
Design
This section presents the design and simulation of
rectangular microstrip patch antenna, for resonant frequency
of 1950 MHz, using EMCoS Antenna VirtualLabTM
electromagnetic simulation software.
2.1 Initial Design
The initial microstrip patch antenna design parameters, patch
length L, patch width W, feed position (xf, yf ) from the center
of the patch, ground plane length Lg and ground plane width
Wg, are estimated, using the Transmission Line model [7]
and the Cavity model of microstrip patch antenna [8]. The
design steps are detailed below.
The first step is to select the width W of the patch radiator.
The optimum value of W is given by,
where,
is the free space wavelength, corresponding to the
resonant frequency fo and
is the dielectric constant of the substrate material.
The second step determines the effective dielectric constant
of air-substrate-air multilayer medium,
where, h is the height or thickness of the substrate.
The third step calculates the electrical elongation of patch
length,
The resonant frequency fo of the TM10 mode is given by,
ol
re
Paper ID: SUB151708 2021
International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064
Index Copernicus Value (2013): 6.14 | Impact Factor (2013): 4.438
Volume 4 Issue 2, February 2015
www.ijsr.net Licensed Under Creative Commons Attribution CC BY
where, c is the speed of light in free space.
The fourth step obtains the physical length L of the patch
resonating at frequency fo,
The fifth step determines the feed position, relative to the
origin, located at the center of the patch,
The sixth step decides the ground plane length Lg and width
Wg, which should be at least
The design parameters estimated using the above six steps,
for a rectangular microstrip patch antenna, resonant at 1950
MHz, which uses RO3003TM
copper clad substrate from
Rogers, USA, are shown in the Table 1. The table also shows
RO3003TM
copper clad substrate parameters [10]. The half
wavelength rectangular microstrip patch antenna is
illustrated in the Fig 1.
Table 1: Initial Design Parameters
Parameter Value in mm RO3003TM
L 43.942995 h 1.524 mm
W 54.392829 εr
3
Lg 53.086995 tan(δ) 0.0013
Wg 63.536829 d 1.3 mm
xf 8.247373 Colour White
yf 0
Figure 1: Rectangular Microstrip Patch Antenna on
RO3003TM
2.2 Simulation and Final Design
The initial antenna design obtained using the Transmission
Line model and the Cavity model, is simply a rough
estimate. It needs further refinements, to achieve the design
specifications. The initial design is refined using computer
simulation. The electromagnetic simulation software EMCoS
Antenna VirtualLabTM
is used for simulation and corrections.
The details of simulation of microstrip patch type antenna
using EMCoS Antenna VirtualLabTM
are given in [9].
The initial antenna model is created from the dimension
values shown in the Table 1. The model is simulated and
obtained results for the antenna parameters, S11, Z11, VSWR
and Smith chart, are compared with those required for the
design specifications. In the first run, the simulation results
for the antenna parameters do not match well with the
antenna parameters of the design specifications. Therefore,
the antenna model is improved by changing any one of
antenna model parameters, the patch dimensions or ground
dimensions or the feed location and the resulting model is
simulated and obtained results are compared again with the
antenna parameters required. The process of changing
antenna model, simulating it and comparing results with the
antenna parameters of the design specifications, is repeated
until a good match between simulation results and the design
specified antenna parameters is obtained.
The final microstrip patch antenna model dimensions and
feed location, obtained using the technique of iteratively
improving antenna model, described previously, is shown in
the Table 2.
Table 2: Final Design Parameters
Parameter Value in mm RO3003TM
L 42.215513 h 1.524 mm
W 54.392829 εr
3
Lg 65 tan(δ) 0.0012
Wg 65 Colour White
xf 8.907163
yf 0
d 1.30
The antenna characteristics for S11 and Z11 are presented in
Fig 2 and Fig 3, respectively. The VSWR and Smith chart
for
the antenna design, are presented in Fig 4 and Fig 5
respectively.
Figure 2: S11 Characteristics
Paper ID: SUB151708 2022
International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064
Index Copernicus Value (2013): 6.14 | Impact Factor (2013): 4.438
Volume 4 Issue 2, February 2015
www.ijsr.net Licensed Under Creative Commons Attribution CC BY
Figure 3: Z11 Characteristics
Figure 4: VSWR
Figure 5: Smith Chart
The results for some important antenna parameters are given
in the Table 3
Table 3: Rectangular Microstrip Patch Antenna Parameters
Antenna Parameter Value Unit
fo 1950 MHz
S11 Minimum -39.0398 dB
VSWR Bandwidth 32 MHz
S11 Bandwidth 34 MHz
Z11 at resonance 51.1144-j0.183245 Ohm
[1] Fabrication of Rectangular Microstrip Patch
Antenna
This section describes the photo-lithographic fabrication of
rectangular microstrip patch antenna designed and simulated
in the earlier section. The dimensions of designed
rectangular microstrip patch antenna are given in the Table 2.
Photo-lithographic method requires ultra violet (UV) light of
suitable wavelength and photo-resist sensitive to this
wavelength. The photo-resist materials are of two types,
positive and negative. The exposed portion of positive photo-
resist dissolves in the photo-resist developer and that of
negative photo-resist hardens. Photo-resist material in the
form of dry negative photo-resist film, to be applied as
lamination to the copper clad substrate and UV A type light,
obtained from insect killer PhilipsTM
fluorescent tube lamp,
are used in the present work. This UV light is centered
around the wavelength of 370 nm [11].
The step by step process for the microstrip patch antenna
fabrication, used in the present work, is illustrated in the Fig.
6 and 7. The first step is computer aided design of the
antenna geometry. A negative of this geometry printed on
transparent sheet serves as the mask. A double sided copper
clad substrate RO3003TM
of dimension 65 mm X 65 mm is
thoroughly cleaned using acetone and dried. Dust particles or
impurities present on the copper clad surface introduce
discontinuity in the etched pattern that alters the resonant
frequency. In the second step, a negative photo-resist film is
laminated to the cleaned and dried copper clad substrate. The
negative mask prepared in the first step is firmly placed on
the photo-resist laminated copper clad substrate. The masked
and photo-resist laminated copper clad substrate is exposed
to ultra violet (UV) light. The third step is to develop the UV
exposed photo-resist laminated copper clad substrate. The
photo-resist exposed to UV light becomes hard and dark blue
in colour while unexposed photo-resist remains light blue
and dissolves in the developer solution. Sodium Carbonate is
used as the developer. Finally, the developed copper clad
substrate is chemically etched by Ferric Chloride FeCl3
solution. The copper parts except underneath the hardened
photo resist dissolve in FeCl3. The etched substrate is rinsed
in running water to remove any etchant and then dried. The
hardened photo-resist is removed using Sodium Hydroxide.
The photo-lithographically fabricated rectangular microstrip
patch antenna is shown in the Fig. 8. The UV Exposure unit
is shown in Fig. 9.
Paper ID: SUB151708 2023
International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064
Index Copernicus Value (2013): 6.14 | Impact Factor (2013): 4.438
Volume 4 Issue 2, February 2015
www.ijsr.net Licensed Under Creative Commons Attribution CC BY
Mask Copper Clad RO3003
TM
Photo-resist Laminated UV Exposed Laminated
Copper Clad RO3003TM
Copper Clad RO3003TM
Figure 6: Photo-lithographic Fabrication Initial Steps
Developed Etched
Final photo-resist removed
Figure 7: Photo-lithographic Fabrication Final Steps
Patch Ground
Figure 8: Rectangular Microstrip Patch Antenna
Figure 9: UV Exposure Unit
3. Conclusions and Discussions
A half wavelength rectangular microstrip patch antenna,
resonant at frequency fo = 1950 MHz, is designed and
simulated on RO3003TM
copper clad substrate. The
microstrip patch antenna dimensions obtained from the
simulation are used to fabricate the antenna. The antenna is
fabricated using photo-lithography technique. The photo-
lithographic fabrication of microstrip patch antenna is
described.
4. Acknowledgements
The authors gratefully acknowledge the evaluation license
granted by EMCoS Ltd., Georgia, for Antenna VirtualLabTM
software. The authors also gratefully acknowledge the
research material support from Rogers Corporation, USA,
for supplying RO3003TM
copper clad substrate material and
literature. DraftSightTM
from Dassault Systemes SolidWorks
Corporation, Massachusetts, USA, has been used in this
work to prepare mask artwork for photo-lithography [12].
The license granted by Dassault Systemes SolidWorks
Corporation, Massachusetts, USA, is gratefully
acknowledged.
References
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Antenna Design Handbook. Artech House, 2001.
[2] E.J. Denlinger. Radiation from Microstrip Resonators
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[3] C. A. Balanis. Antenna Theory: Analysis and Design, 3rd
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[4] EMCoS Antenna VLab [Online]. Available:
http://www.emcos.com
[5] R. F. Harrington, Field Computation by Moment Methods.
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[6] I. J. Bahl and P Bhartia. Design Considerations in Microstrip
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[7] H. Pues and A. Van de Capelle, “Accurate transmission-line
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[10] “RO3000 Series Circuit Materials”, Rogers Corporation, USA.
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[11] Actinic BL TL-D 18W/10 1SL. Royal Philips, 2014.
[12] DraftSight [Online]. Available: http://www.solidworks.com
Paper ID: SUB151708 2024